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The Dynaco Tube Audio Forum

Dedicated to the restoration and preservation of all original Dynaco tube audio equipment - Customer support for Tubes4hifi VTA tube amp and preamp kits and all Dynakitparts.com products


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    SDS labs capacitor board hum Mark iii

    daniel a
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    daniel a


    Posts : 8
    Join date : 2013-12-26
    • Post n°1

    SDS labs capacitor board hum Mark iii Empty SDS labs capacitor board hum Mark iii

    Post by daniel a Fri Dec 27, 2013 1:52 pm

    Any ideas as to why an  SDS capacitor  board for a Mark iii would have loud hum 10 seconds after
    turning amp on. Put old quad capacitor back in and amp was fine All parts are in correct position and polarity    soldered points are good.    Hum is from speaker
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    GP49
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    GP49


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    Join date : 2009-04-30
    Location : East of the sun and west of the moon
    • Post n°2

    SDS labs capacitor board hum Mark iii Empty Re: SDS labs capacitor board hum Mark iii

    Post by GP49 Fri Dec 27, 2013 1:56 pm

    Probably a bum capacitor. It happens...
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    peterh
    peterh
    peterh


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    Location : gothenburg, sweden
    • Post n°3

    SDS labs capacitor board hum Mark iii Empty Re: SDS labs capacitor board hum Mark iii

    Post by peterh Fri Dec 27, 2013 2:46 pm

    daniel a wrote:Any ideas as to why an  SDS capacitor  board for a Mark iii would have loud hum 10 seconds after
    turning amp on. Put old quad capacitor back in and amp was fine All parts are in correct position and polarity    soldered points are good.    Hum is from speaker
    Keep the old cap, return SDS cap and order a new cap from tubes4hifi ( or dynakitparts)
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    kygeezer
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    kygeezer


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    Join date : 2012-11-30
    • Post n°4

    SDS labs capacitor board hum Mark iii Empty Re: SDS labs capacitor board hum Mark iii

    Post by kygeezer Fri Dec 27, 2013 3:57 pm

    Don't give up on the SDS board! I rebuilt two Mark IIIs and used SDS boards on both. They are both dead quiet. Be sure you follow the grounding instructions and be sure you don't have any solder bridges which are easy to do on those boards. Good luck!
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    daniel a
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    daniel a


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    • Post n°5

    SDS labs capacitor board hum Mark iii Empty Re: SDS labs capacitor board hum Mark iii

    Post by daniel a Fri Dec 27, 2013 7:24 pm

    The instructions from triode electronics said nothing about grounding the board. Called them and they recommended grounding the board. said their instructions need updated  really
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    GP49
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    GP49


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    • Post n°6

    SDS labs capacitor board hum Mark iii Empty Re: SDS labs capacitor board hum Mark iii

    Post by GP49 Sat Dec 28, 2013 12:33 am

    daniel a wrote:The instructions from triode electronics said nothing about grounding the board. Called them and they recommended grounding the board. said their instructions need updated  really


    RECOMMEND grounding the board? The capacitors MUST have their low side grounded. What am I missing here???

     What a Face affraid confused scratch
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    • Post n°7

    SDS labs capacitor board hum Mark iii Empty Re: SDS labs capacitor board hum Mark iii

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